The present invention relates to a vehicular indicator lamp, and particularly to the structure of the reflective surface of the reflector of a vehicular indicator lamp.
In recently designed vehicular indicator lamps a transparent lens has been used for the front lens for imparting a visual impression of clarity to the lamp, while the reflective surface of the reflector has commonly been formed with a plurality of fisheye-lens-shaped reflective elements so as to provide desired light distribution properties for the lamp.
When this type of lamp is viewed from the front, the reflective elements appear through the transparent lens to shine in a scattered pattern. However, when the point of observation is moved from a position directly in front of the lamp up or down or to the left or right, there is practically no change in the observed brightness pattern of the reflective surface. It has been desired though to provide a better visual impression to the observer and to enhance the design originality of the lamp.
Accordingly, as shown in FIG. 12, a vehicular lamp has been proposed in which the reflective surface 2a of a reflector 2 is formed of a plurality of reflective elements 2s arranged in a pattern of vertical stripes, with the horizontal cross section thereof being established as a wavy pattern of predetermined shape. With this lamp, when the point of observation is moved from a position directly in front of the lamp to the left or right, the observed brightness pattern of the reflective surface 2a will change.
However, even in a lamp structure having this type of vertically striped wavy reflective surface, when the point of observation is vertically moved from a position directly in front of the lamp, there is practically no change in the observed brightness pattern of the-reflective surface 2a. As a result, improvements in the design originality of the lamp are still desired.
Moreover, concerning the light distribution properties of a vehicular indicator lamp, it is necessary to irradiate light that is diffused not only in the horizontal direction but also in the vertical direction to the front of the lamp. If the above-described reflector structure that has a vertically striped wavy reflective surface is employed, a problem arises in that, as shown in FIG. 12, it becomes necessary to additionally provide diffusion lens elements 4s arranged in horizontal stripes on the inner surface of the front lens 4, as a result of which the visual impression of clarity of the lamp is diminished.
The present invention has been conceived in consideration of the foregoing situation. Accordingly, it is an object of the invention to provide a vehicular indicator lamp that provides a novel visual impression to an observer when the point of observation is moved either horizontally or vertically, while ensuring a visual impression of clarity.
The present invention achieves the aforementioned object by a novel design of the configuration of the cross section of the reflective surface of the reflector.
More specifically, the vehicular indicator lamp according to the present invention is provided with a light source bulb, a reflector having a reflective surface for reflecting light from the light source bulb forward, and a front lens provided forward of the reflector, which is characterized in that the reflective surface is divided into a plurality of segments in a grid pattern, each of which is allocated a reflective element, and the reflective surface is formed as a two-dimensional wavy surface in which concave surface reflective elements and convex surface reflective elements are alternately repeated in two directions along the grid.
There is no particular limitation on the pattern of the above-mentioned grid. For example, it is possible to employ an orthogonal grid formed by two straight lines orthogonal to one another, a slanted grid in which the lines intersect at a slant, an annular grid formed from a plurality of straight lines arranged in a radial shape, and a plurality of curved lines arranged in a concentric shape.
Provided that adjacent concave surface reflective elements and convex surface reflective elements are connected together with no difference in height therebetween in either grid direction, the two-dimensional wavy surface may be a surface on which a line is created at the portion connecting the two types of reflective elements. Moreover, there is no particular restriction concerning the value of the radius of curvature of each concave surface reflective element and each concave surface reflective element forming the two-dimensional wavy surface. Furthermore, the two-dimensional wavy surface may be applied to the entirety of the reflective surface or to only a portion of the reflective surface
As described above, the reflective surface of the reflector of the vehicular indicator lamp according to the invention is formed by dividing the reflective surface into a plurality of segments in a grid pattern, each of which is allocated a reflective element. The reflective surface is formed as a two-dimensional wavy surface in which concave surface reflective elements and convex surface reflective elements are alternately repeated in two directions along the grid, thus providing the following operation and effect.
Namely, in the case where the reflective surface of the illuminated lamp is viewed from the front, if the point of observation is moved vertically or horizontally, the bright portions (i.e., those portions where light from the light source bulb is reflected and appears to shine) of the convex surface reflective elements move in the same direction as the direction in which the point of observation has moved. In contrast, the bright portions of the concave surface reflective elements move in the opposite direction to the direction in which the point of observation has moved. Therefore, the brightness pattern of the reflective surface changes dynamically to accompany the movement of the point of observation, and the brightness pattern as seen from directly in front of the lamp, the brightness pattern as seen from the left side (or from the top), and the brightness pattern as seen from the right side (or from the bottom) are all different. Moreover, the brightness pattern of the reflective surface changes dynamically as the point of observation changes, which allows the observer to perceive a strong glittering sensation.
Even in the OFF state of the lamp, when light irradiated from outside the lamp is reflected by the reflective elements, the resultant brightness pattern changes as the point of observation moves. This provides the observer with a strong glittering sensation.
Moreover, because the above-described reflective surface is formed as a two-dimensional wavy surface, it is possible to obtain light that is diffused in both the vertical and horizontal directions from the reflected light of the reflector. As a result, the front lens can be formed from a transparent or substantially transparent lens. It is therefore possible to ensure the impression of clarity of the lamp.
According to the present invention where the impression of clarity of the lamp is ensured, even if the point of observation is moved in either the vertical or horizontal directions, a novel impression is given to the observer, and consequently the appearance of the lamp is improved.
The pitches of the above-mentioned segments may be either uniform or varied. In the latter case, if the pitch of the segments gradually increases away from the optical axis of the reflector, the interval between bright portions increases away from the optical axis of the reflector. As a result, it is possible to give an impression of depth to the observer.
In the above-described structure, if the two-dimensional wavy surface is formed with a paraboloid of revolution as a reference surface having the optical axis of the reflector as its central axis, it is possible to diffuse reflected light from the reflector vertically and horizontally around the optical axis. Therefore, it is possible to easily obtain the desired lamp light distribution properties.